cGAS recognizes HTLV-1 RTI and induces STING-dependent innate immune responses / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate whether cyclic GMP-AMP synthase ( cGAS ) , a cytosolic DNA sensor, could recognize the reverse transcription intermediate and induce the subsequent signaling path-way during the infection of human T cell leukemia virus type 1 ( HTLV-1 ) . Methods Biotin-labeled ssDNA90, a reverse transcription intermediate of HTLV-1, was transfected into HeLa cells and the interac-tion between it and cGAS was detected by co-immunoprecipitation experiments. HeLa cells were co-cultured with HTLV-1-positive MT2 cells and the interaction between cGAS and stimulator of interferon genes ( STING) was analyzed by co-immunoprecipitation experiments. The expression of STING in HeLa cells was silenced by siRNA. cGAS was transfected into the HeLa cells 24 h after the silencing and after 24 h, these cells were co-cultured with MT2 cells for another 24 h. Real-time PCR assay was used to measure the ex-pression of IFN-β, RANTES ( regulated upon activation, normal T-cell expressed, and secreted) , TNF-α, HTLV-1 protein Tax, p19 and HBZ. Immunoblot assay was performed to evaluate the phosphorylation of IRF3 and p65 in HeLa cells. Results cGAS interacted with ssDNA90. cGAS interacted with STING in the cytoplasm. In STING-silenced HeLa cells, cGAS transfection had no influence on the expression of IFN-β, RANTES , TNF-α, Tax , p19 or HBZ , nor did it affect the phosphorylation of IRF3 or p65 . Conclusions cGAS interacted with HTLV-1 RTI ssDNA90 and activated STING-dependent innate immune responses.